1. Field of the Invention
The present invention relates to a hybrid vehicle equipped with a plurality of prime movers for running the vehicle.
2. Related Art
In the prior art, there have been developed a hybrid vehicle which is intended to improve an overall efficiency by combining a plurality of prime movers while exploiting the merits and compensating the demerits of the individual prime movers. One example of this hybrid vehicle is disclosed in JPA-7-186748.
The hybrid vehicle, as disclosed, is equipped with an engine and a motor-generator as the prime movers. The motor-generator is given a power running function to convert an electric energy into a kinetic energy, and a regenerative function to establish a regenerative braking force by converting a kinetic energy into an electric energy.
Moreover, the hybrid vehicle is constructed such that the drive force of the engine is transmitted either the front wheels or the rear wheels whereas the drive force of the motor-generator is transmitted to the wheels to which is not transmitted the drive force of the engine.
On the other hand, this hybrid vehicle is equipped with a controller for controlling its running state. To this controller, there are inputted a variety of signals for indexing the running state, such as the RPM of the engine, the throttle opening, the steering angle, the stroke of depression of the brake, the stroke of depression of the accelerator pedal or the gear position. The motor-generator is controlled by this controller on the basis of those signals.
In a straight running state or a running state at a small steering angle of the hybrid vehicle, for example, the drive force at an acceleration or the braking force at a deceleration is detected. Moreover, a shortage of the drive force, if detected, is assisted with the drive force of the motor-generator. On the other hand, a shortage of the braking force, if detected, is assisted with the regenerative braking force of the motor-generator.
However, what is done by the hybrid vehicle disclosed in the aforementioned Laid-Open is only to assist the shortage of the drive force of the engine or the braking force of the vehicle by the motor-generator. In short, no consideration is taken into the transient situation which accompanies the changes in the acting states of the engine and the transmission connected to the engine. Therefore, it cannot be said that the output of the motor-generator, as used in parallel with the engine, functions sufficiently for all the various situations that will occur from the start to the end of the run of the vehicle. This exerts a restriction upon the improvements in the running performance, the drivability or the riding comfort.
A main object of the present invention is to provide a hybrid vehicle which can exploit, during one prime mover is active, the output of another prime mover effectively as the drive force or braking force of the vehicle on the basis of the change in the active state of the active prime mover or a power transmission unit connected to the former.
According to a hybrid vehicle having a first characteristic construction of the present invention, if a braking demand in an idling state of a first prime mover such as an engine is detected while the vehicle is running, the braking force is assisted with the regenerative braking force of a second prime mover such as a motor-generator thereby to suppress the rise in the vehicle speed. As a result, the braking operation by the driver and its frequency are decreased to improve the braking performance and the drivability.
According to a hybrid vehicle having a second characteristic construction of the present invention, if an obstruction around the vehicle is detected, the vehicle is suppressed from approaching the obstruction by the regenerative braking force of the second prime mover such as the motor-generator. As a result, the braking operation by the driver and its frequency are decreased to improve the braking performance and the drivability.
According to a hybrid vehicle having a third characteristic construction of the present invention, if the distance between the vehicle of the driver and another preceding vehicle is shortened, the braking force of the own vehicle is increased to hold the distance between vehicles constant by the regenerative braking force of the second prime mover such as the motor-generator. As a result, the braking operation by the driver and its frequency are decreased to improve the braking performance and the drivability.
According to a hybrid vehicle having a fourth characteristic construction of the present invention, if the vehicle is run by the output torque of one prime mover amplified by a torque converter, the output of another prime mover is added to the drive force of the vehicle on the basis of the torque of the output member of the torque converter. As a result, the transient change in the drive force, as based on the action of the torque converter, is assisted with the output of another prime mover to improve the running performance and the drivability.
According to a hybrid vehicle having a fifth characteristic construction of the present invention, the output of another active prime mover is added to the drive force of the vehicle during a downshift of an automatic transmission. As a result, the transient change in the drive force according to the change in the output torque of the automatic transmission is assisted with the output of another prime mover to improve the acceleration responsiveness of the vehicle thereby to improve the running performance and the drivability.
According to a hybrid vehicle having a sixth characteristic construction of the present invention, if a speed changing frequency of the automatic transmission exceeds a predetermined value, the output of another active prime mover is added to the drive force of the vehicle. In short, the running state of the vehicle makes it difficult to change the speed of the automatic transmission. As a result, the vibration due to the frequent speed change of the automatic transmission, i.e., the hunting is prevented to improve the riding comfort and the drivability.
According to a hybrid vehicle having a seventh characteristic construction of the present invention, the output of another prime mover is added to the drive force of the vehicle during the upshift of the automatic transmission. As a result, the transient change in the drive force due to the upshift of the automatic transmission can be suppressed to prevent the shift shock thereby to improve the riding comfort, the running performance and the drivability.
According to a hybrid vehicle having an eighth characteristic construction of the present invention, if a speed change of a transmission is detected, the output of another prime mover is added to the drive force of the vehicle. As a result, the transient change in the drive force due to the speed change of the transmission can be suppressed to prevent the shift shock thereby to improve the riding comfort, the running performance and the drivability.
According to a hybrid vehicle having a ninth characteristic construction of the present invention, if the change in the drive force of the vehicle is detected by the speed change of the transmission, the changing range of the drive force of the vehicle is suppressed by the output of another prime mover. As a result, the transient change in the drive force due to the speed change of the transmission can be suppressed to improve the riding comfort, the running performance and the drivability.
According to a hybrid vehicle having a tenth characteristic construction of the present invention, if a demand for increasing the drive force of the vehicle is detected with an input member and an output member being connected by a lockup clutch, the output of another prime mover is added to the drive force of the vehicle. As a result, it is simultaneously possible to keep the torque transmission efficiency by the coupling of the lockup clutch, to prevent the vibration and to improve the accelerating ability, thereby to improve the running performance, the riding comfort and the drivability.
According to a hybrid vehicle having an eleventh characteristic construction of the present invention, if a demand for stopping the vehicle is detected during an idling of a first prime mover such as the engine, the creep torque, as outputted from a starting unit, is suppressed by the regenerative braking force of a second prime mover such as the motor-generator. As a result, the braking operation by the driver and its frequency are decreased to improve the braking performance and the drivability.
According to a hybrid vehicle having a twelfth characteristic construction of the present invention, if the driver is inattentive even when the driver""s intention is to move the vehicle gradually forward or backward, an alarm is raised to stop the inattention. As a result, the braking operation by the driver and its frequency are reduced to improve the braking performance and the drivability.
According to a hybrid vehicle having a thirteenth characteristic construction of the present invention, if it is detected while the vehicle is run by the output of one prime mover that the prime mover is changed from a shut state to a fed-state of the fuel, the output of another prime mover is added to the drive force of the vehicle. As a result, the shortage of the drive force of the vehicle due to a delay in the exposition timing of the prime mover in the fed state of the fuel is assisted with the output of another prime mover so that the transient accelerating ability is improved to improve the running performance and the drivability.
The above and further objects and novel features of the present invention will more fully appear from the following detailed description when the same is read with reference to the accompanying drawings. It is to be expressly understood, however, that the drawings are for the purpose of illustration only and are not intended as a definition of the limits of the invention.